Dew point and nightly lows

[Glacierx]

Originally Posted by george960

In summer, I would say that the overnight low is usually a little higher than the afternoon dew point.

I think depends on where you live. In North America, east of Rockies = higher temperature than dewpoint; west of the Rockies = lower temperature than dewpoint (generally speaking).

Example: Here in southern British Columbia a place at 49 degrees N at 700 m elevation will have colder nights in the summer than a place in the northeast of British Columbia at 56 degrees N at 700 m elevation because that northern community is on the east side of the Rockies.

[Cambium]

Originally Posted by nei

Here, assuming there's no rain or front systems passing through, the nightly lows will usually be close to the late afternoon dew point.

Just realized you asked about the late afternoon dewpoints and min temps. Not the minimum dewpoints.

Issue with this is, sometimes the max dewpoints come at night not in the afternoon. We would have to look at the hourly data to get a specific afternoon dewpoint temp.

Here's Northern Connecticut (BDL) Minimum Temps vs the Maximum Dewpoints for each day of January 2013.

Is this considered "close" to you or does this show something else?

[nei]

Here's an example recently:

San Francisco yesterday afternoon: dew point of 15°F
Low next morning: 37°F

[AdriannaSmiling]

Originally Posted by nei

Here's an example recently:

San Francisco yesterday afternoon: dew point of 15°F
Low next morning: 37°F

Our microclimates kick in again; this time with San Francisco being the "hot spot" for overnight lows- most places in the Bay Area went below freezing with San Jose at 25 F and Santa Rosa at 20 F, but all those locations will have the similar daytime highs in the upper 40s. The afternoon dewpoints were also rather similar in the mid teens. Of course, this pales in comparison to the differences in daytime highs during the summer when San Francisco's can be 60 F and San Jose's 90 F but still noteworthy because San Francisco is the only places that escapes the freeze warnings. We get our freezes from dry air masses so that's why the dewpoints drop in the afternoon. When the clouds come, the overnight lows skyrocket, and the afternoon dewpoints go way up as well, making snow an extremely rare event here despite a few freezes each winter.

[nei]

Was it cloudy overnight in San Francisco with the low dew points? I think so?